Alternate Heating Systems, Inc announces that the Wood Gun wood gasification boiler is available as a UL Listed solid fuel hydronic heater. UL testing was completed some time ago, and is available as an option on some stock units, and on new orders. Many local jurisdictions, and some states, require this. UL listed boilers are also necessarily ASME certified as well. ASME Code boilers are $600 more. The UL listing is an additional $600.